1. Field of the Invention
Embodiments of the present invention generally relate to gas distribution assemblies for chemical vapor deposition chambers. More particularly, embodiments of the invention relates to blocker plates that resist deposition.
2. Description of the Related Art
Sub-quarter micron multilevel metallization is one of the key technologies for the next generation of very large scale integration (VLSI). The multilevel interconnects that lie at the heart of this technology require planarization of high aspect ratio apertures, including contacts, vias, lines or other features having aperture widths less than 0.25 μm and aperture depths greater than the aperture widths. Reliable formation of these interconnects is very important to the success of VLSI and to the continued effort to increase circuit density and quality on individual substrates and die.
Metal interconnects are typically formed by physical vapor deposition (PVD), chemical vapor deposition (CVD), electrochemical deposition and/or sequential combinations thereof. CVD metal films, such as CVD aluminum films, provide excellent conformal coverage of features. CVD of aluminum films is typically performed with a bubbled precursor which is transported with means of a carrier gas into the reactor. The bubbled precursor is typically directed though a gas distribution assembly including a showerhead and a blocker plate situated near the top of the chamber. The precursor reacts to form a layer of material on the surface of a substrate that is positioned on a substrate support in the chamber. However, some of the precursor by-products may react to deposit the material on the interior surfaces of the chamber, forming contaminating deposits. Over time, the contaminating deposits may flake off and damage a substrate during processing or affect chamber performance to the extent that the chamber cannot perform reliably. The generation of the contaminating particles may be accelerated depending on the choice of the CVD precursor gas.
The formation of deposits on components of the gas distribution assembly, such as the blocker plate, is particularly problematic. Because of the large surface area of the blocker plate and the proximity of the blocker plate to the substrate, deposits that are formed on the blocker plate may detach and land on the substrate.
Attempts have been made to chemically clean blocker plates. However, the chemical solutions used to clean the blocker plates often leave contaminating residues that must be removed from the blocker plates.
Therefore, there remains a need for a method of reducing the formation of contaminating deposits on chamber components such as blocker plates.